Find the frequency of each element in an array in swift

Swift program for Find the frequency of each element in an array. Here problem description and other solutions.

``````import Foundation
class Occurrence
{
// Function which is display array elements
static func display(_ arr: [Int])
{
var i: Int = 0;
while (i < arr.count)
{
print(" ", arr[i], terminator: " ");
i += 1;
}
print(terminator:"\n");
}
// Count occurrence of given array
static func frequency(_ arr: [Int])
{
// Display given array
Occurrence.display(arr);
// Create a empty map
var map: [Int: Int] = [Int: Int]();

for data in arr
{
if (map.keys.contains(data))
{
// When key exists then update value
map[data] = map[data]! + 1;
}
else
{
map[data] = 1;
}

}
print(" Occurrence ");
//  Display calculated result
for key in Array(map.keys)
{
print(" ",key, " : ",map[key]!);
}
}
static func main(_ args: [String])
{
// Array element
let arr: [Int] = [1, 3, 2, 1, 4, 2, 7, 9, 1, 3, 3, 4, 7];
Occurrence.frequency(arr);
}
}
Occurrence.main([String]());``````

Output

``````  1   3   2   1   4   2   7   9   1   3   3   4   7
Occurrence
9  :  1
7  :  2
2  :  2
3  :  3
1  :  3
4  :  2``````

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